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.\" Author: Dave Chapeskie
.\"
.Dd January 18, 2021
.Dt NG_SOURCE 4
.Os
.Sh NAME
.Nm ng_source
.Nd netgraph node for traffic generation
.Sh SYNOPSIS
.In sys/types.h
.In netgraph/ng_source.h
.Sh DESCRIPTION
The
.Nm source
node acts as a source of packets according to the parameters set up
using control messages and input packets.
The
.Nm
node type is used primarily for testing and benchmarking.
.Sh HOOKS
The
.Nm source
node has two hooks:
.Va input
and
.Va output .
The
.Va output
hook must remain connected, its disconnection will shutdown the node.
.Sh OPERATION
The operation of the node is as follows.
Packets received on the
.Va input
hook are queued internally.
When
.Va output
hook is connected,
.Nm
node assumes that its neighbour node is of
.Xr ng_ether 4
node type.
The neighbour is queried for its interface name.
The
.Nm
node then uses queue of the interface for its evil purposes.
The
.Nm
node also disables
.Va autosrc
option on neighbour
.Xr ng_ether 4
node.
If interface name cannot be obtained automatically, it should
be configured explicitly with the
.Dv NGM_SOURCE_SETIFACE
control message, and
.Va autosrc
should be turned off on
.Xr ng_ether 4
node manually.
.Pp
If the node is connected to a netgraph network, which does not
terminate in a real
.Xr ng_ether 4
interface, limit the packet injection rate explicitly with the
.Va NGM_SOURCE_SETPPS
control message.
.Pp
Upon receipt of a
.Dv NGM_SOURCE_START
control message the node starts sending
the previously queued packets out the
.Va output
hook on every clock tick as fast
as the connected interface will take them.
While active, on every clock tick the node checks the available space
in the interface queue and sends that many packets out its
.Va output
hook.
Once the number of packets indicated in the start message has been
sent, or upon receipt of a
.Dv NGM_SOURCE_STOP
message, the node stops sending data.
.Sh CONTROL MESSAGES
This node type supports the generic control messages as well as the following,
which must be sent with the
.Dv NGM_SOURCE_COOKIE
attached.
.Bl -tag -width foo
.It Dv NGM_SOURCE_GET_STATS Pq Ic getstats
Returns a structure containing the following fields:
.Bl -tag -width ".Va elapsedTime"
.It Va outOctets
The number of octets/bytes sent out the
.Va output
hook.
.It Va outFrames
The number of frames/packets sent out the
.Va output
hook.
.It Va queueOctets
The number of octets queued from the
.Va input
hook.
.It Va queueFrames
The number of frames queued from the
.Va input
hook.
.It Va startTime
The time the last start message was received.
.It Va endTime
The time the last end message was received or
the output packet count was reached.
.It Va elapsedTime
Either
.Va endTime Li \- Va startTime
or current time
\-
.Va startTime .
.El
.It Dv NGM_SOURCE_CLR_STATS Pq Ic clrstats
Clears and resets the statistics returned by
.Ic getstats
(except
.Va queueOctets
and
.Va queueFrames ) .
.It Dv NGM_SOURCE_GETCLR_STATS Pq Ic getclrstats
As
.Ic getstats
but clears the statistics at the same time.
.It Dv NGM_SOURCE_START Pq Ic start
This message requires a single
.Vt uint64_t
parameter which is the number of packets to
send before stopping.
Node starts sending the queued packets out the
.Va output
hook.
The
.Va output
hook must be connected and node must have
interface configured.
.It Dv NGM_SOURCE_STOP Pq Ic stop
Stops the node if it is active.
.It Dv NGM_SOURCE_CLR_DATA Pq Ic clrdata
Clears the packets queued from the
.Va input
hook.
.It Dv NGM_SOURCE_SETIFACE Pq Ic setiface
This message requires the name of the interface
to be configured as an argument.
.It Dv NGM_SOURCE_SETPPS Pq Ic setpps
This message requires a single
.Vt uint32_t
parameter which puts upper limit on the amount of packets
sent per second.
.It Dv NGM_SOURCE_SET_TIMESTAMP Pq Ic settimestamp
This message specifies that a timestamp (in the format of a
.Vt "struct timeval" )
should be inserted in the transmitted packets.
This message requires a structure containing the following fields:
.Bl -tag -width ".Va offset"
.It Va offset
The offset from the beginning of the packet at which the timestamp is to be
inserted.
.It Va flags
Set to 1 to enable the timestamp.
.El
.It Dv NGM_SOURCE_GET_TIMESTAMP Pq Ic gettimestamp
Returns the current timestamp settings in the form of the structure described
above.
.It Dv NGM_SOURCE_SET_COUNTER Pq Ic setcounter
This message specifies that a counter should be embedded in transmitted
packets.
Up to four counters may be independently configured.
This message requires a structure containing the following fields:
.Bl -tag -width ".Va increment"
.It Va offset
The offset from the beginning of the packet at which the counter is to be
inserted.
.It Va flags
Set to 1 to enable the counter.
.It Va width
The byte width of the counter.
It may be 1, 2, or 4.
.It Va next_val
The value for the next insertion of the counter.
.It Va min_val
The minimum value to be used by the counter.
.It Va max_val
The maximum value to be used by the counter.
.It Va increment
The value to be added to the counter after each insertion.
It may be negative.
.It Va index
The counter to be configured, from 0 to 3.
.El
.It Dv NGM_SOURCE_GET_COUNTER Pq Ic getcounter
This message requires a single
.Vt uint8_t
parameter which specifies the counter to query.
Returns the current counter settings in the form of the structure described
above.
.El
.Sh SHUTDOWN
This node shuts down upon receipt of a
.Dv NGM_SHUTDOWN
control message, when all hooks have been disconnected, or when the
.Va output
hook has been disconnected.
.Sh EXAMPLES
Attach the node to an
.Xr ng_ether 4
node for an interface.
If
.Nm ng_ether
is
not already loaded you will need to do so.
For example, these commands
load the
.Nm ng_ether
module and attach the
.Va output
hook of a new
.Nm source
node to
.Va orphans
hook of the
.Li bge0:
.Nm ng_ether
node.
.Bd -literal -offset indent
kldload ng_ether
ngctl mkpeer bge0: source orphans output
.Ed
.Pp
At this point the new node can be referred to as
.Dq Li bge0:orphans .
The
node can be given its own name like this:
.Pp
.Dl "ngctl name bge0:orphans src0"
.Pp
After which it can be referred to as
.Dq Li src0: .
.Pp
Once created, packets can be sent to the node as raw binary data.
Each packet must be delivered in a separate netgraph message.
.Pp
The following example uses a short Perl script to convert the hex
representation of an ICMP packet to binary and deliver it to the
.Nm source
node's
.Va input
hook via
.Xr nghook 8 :
.Bd -literal -offset indent
perl -pe 's/(..)[ \et\en]*/chr(hex($1))/ge' <<EOF | nghook src0: input
ff ff ff ff ff ff 00 00 00 00 00 00 08 00 45 00
00 54 cb 13 00 00 40 01 b9 87 c0 a8 2b 65 0a 00
00 01 08 00 f8 d0 c9 76 00 00 45 37 01 73 00 01
04 0a 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 14 15
16 17 18 19 1a 1b 1c 1d 1e 1f 20 21 22 23 24 25
26 27 28 29 2a 2b 2c 2d 2e 2f 30 31 32 33 34 35
36 37
EOF
.Ed
.Pp
To check that the node has queued these packets you can get the node
statistics:
.Bd -literal -offset indent
ngctl msg bge0:orphans getstats
Args:   { queueOctets=64 queueFrames=1 }
.Ed
.Pp
Send as many packets as required out the
.Va output
hook:
.Pp
.Dl "ngctl msg bge0:orphans start 16"
.Pp
Either wait for them to be sent (periodically fetching stats if desired)
or send the stop message:
.Pp
.Dl "ngctl msg bge0:orphans stop"
.Pp
Check the statistics (here we use
.Ic getclrstats
to also clear the statistics):
.Bd -literal -offset indent
ngctl msg bge0:orphans getclrstats
Args:   { outOctets=1024 outFrames=16 queueOctets=64 queueFrames=1
startTime={ tv_sec=1035305880 tv_usec=758036 } endTime={ tv_sec=1035305880
tv_usec=759041 } elapsedTime={ tv_usec=1005 } }
.Ed
.Pp
The times are from
.Vt "struct timeval" Ns s ,
the
.Va tv_sec
field is seconds since
the Epoch and can be converted into a date string via TCL's [clock
format] or via the
.Xr date 1
command:
.Bd -literal -offset indent
date -r 1035305880
Tue Oct 22 12:58:00 EDT 2002
.Ed
.Sh SEE ALSO
.Xr netgraph 4 ,
.Xr ng_echo 4 ,
.Xr ng_hole 4 ,
.Xr ng_tee 4 ,
.Xr ngctl 8 ,
.Xr nghook 8
.Sh HISTORY
The
.Nm
node type was implemented in
.Fx 4.8 .
.Sh AUTHORS
.An Dave Chapeskie
